Muscarinic receptor signaling in the pathophysiology of asthma and COPD

Respiratory Research

Table 2 Muscarinic regulation of (airway) inflammation.

Cell type	Presence of muscarinic receptors, ChAT and/or acetylcholine	Functional effects of acetylcholine
T lymphocyte	Muscarinic receptors (M₁-M₅ *) ChAT Acetylcholine	Increased cytotoxicity Cytokine production Proliferation	[2, 83, 92]
B lymphocyte	Muscarinic receptors (M₁-M₅ *) ChAT Acetylcholine	Proliferation	[2, 83]
Mast cell	Muscarinic receptors (M₁) ChAT Acetylcholine	Inhibition of histamine release	[2, 136, 137]
Neutrophil	Muscarinic receptors (M₁/M₂/M₃) ChAT	Chemotaxis LTB₄ production #	[93, 138]
Eosinophil	Muscarinic receptors (M₁) ChAT	unknown	[93, 138]
Macrophage/monocyte	Muscarinic receptors (M₁/M₂/M₃) ChAT Acetylcholine	LTB₄ production #	[2, 83, 93]
Bronchial epithelium	Muscarinic receptors (M₁/M₃) ChAT Acetylcholine	Release of monocyte, eosinophil and neutrophil chemotactic factors	[95, 96, 98]
Airway smooth muscle	Muscarinic receptors (M₂/M₃) ChAT	Pro-inflammatory gene expression	[2, 8, 99]

* Further characterization is necessary: putative presence of muscarinic M₁ – M₅ receptors shows high variability and is based on their presence in mononuclear leukocytes [83].
# Presence of muscarinic receptors on macrophages and neutrophils suggests their involvement in LTB₄ production by sputum cells [93].

ISSN: 1465-993X